A comprehensive assessment of the circulation of the lymph node involved by metastatic disease will be done, including the following parameters: microcirculatory morphology, regional blood flow, volume of the vascular bed and angiogenesis. The present study builds upon our earlier work and will employ the methods of microangiography, isotope-labeled microsphere distribution RbCl85 exchange, quantitative morphometry, and autoradiography. The animal model is the rabbit popliteal lymph node involved by metastatic Vx2 cancer. The effect of the circulation of the lymph node on the inception and growth of metastasis will be valuable in understanding tumor dissemination, and the alteration of the microcirculatory response could have therapeutic implications. BIBLIOGRAPHIC REFERENCE: Microangiography of the White Pulp of the Spleen: AE Dubreuil MD, PG Herman MD, NL Tilney MD, HZ Mellins MD. Am J Roentgen, 123:427-432, February, 1975.